Liquid compass



J. L. HASSEL LIQUID COMPASS Filed NOV. 10, 1932 Patented Oct. 29, 1935 UNITED STATES Application November 10, 1932, Serial No. 642,105 In Sweden November 11, 1931 2 Claims.

It is known to provide liquid compasses with an expansion chamber to allow for the expansion and contraction of the enclosed liquid due to variations of the temperature. Such device is per se satisfactory but it is generally too expensive for use in hand compasses for military, touristing and sporting purposes.

This invention relates to an improved liquid compass especially adapted for military and sporting purposes which is simple and reliable in its construction and which can be manufactured at a low cost and notwithstanding allows for a satisfactory compensation of the variations of the volume of the enclosed liquid.

The invention consists, chiefly, in this that the transparent cover of the liquid chamber of the compass is yielding by being manufactured of an elastic material such as celluloid, cellon, cellophan, or the like. Such a cover is sufliciently yielding to allow for any variations of the volume of the enclosed liquid without risk of the pressure of the enclosed liquid being increased in such degree that the cover is injured or of liquid being pressed out through the tightening means of the cover.

In the accompanying drawing I have shown some embodiments of my invention. Fig. 1 shows a vertical longitudinal section of a compass for sporting purposes according to my invention.

Figs. 2 and 3 show modifications of the cover of the liquid chamber of the compass.

Referring to Fig. 1 of the drawing, I is the main body of the compass containing a liquid chamber 2 covered by a yielding cover 4 of celluloid or other similar elastic transparent material.

The chamber 2 is filled with petroleum or other liquid which does not act as a solvent for celluloid or other material used in the manufacture of the cover. The cover 4 is preferably provided with a downwardly extending angular flange 4| the lowermost plane portion of which is fastened to the body i by means of a ring 5 and screws (not shown). Above the cover 4 and the ring 5 a a hood I with protecting glass 6 is provided.

The compass needle 3 is in its middle portion provided with a journal or cap 9 by means of which the needle is mounted on a pivot l0. Normally the cover is situated so nearly to the needle that the latter cannot fall off from its pivot III. When however the cover on account of the ex pension of the enclosed liquid is bent outwards the needle may possibly fall down from the pivot. In order to prevent the needle from failing oil from its pivot the cover 4 may be provided on its 10 inner side with guiding means for the needle or its cap, for instance in the form of an angular flange 8 which surrounds the cap 9 without checking the regular movements of the needle on its pivot Hi. iii

In Fig. 2 I have shown a modification oi the cover in which the guiding means for the needle consists of a pin H secured in the centre of the cover and engaging a corresponding recess in the upper side of cap 9 of the compass needle. 20

Fig. 3 shows another modification in which the guiding means consists of an outwardly pressed portion l2 of the cover at the centre of the latter,

said portion enclosing the upper portion of the cap 9 of the needle without positively engaging 25 said cap. Also other modifications are, of course, possible without departing from the scope of the invention.

What I claim is:

1. A liquid compass, comprising a main body, 30 having a chamber for liquid formed therein, a compass needle movably joumaled in said chamher, and a yielding cover of transparent material on said chamber, said cover consisting of a substantially flat disc having an L-shaped flange 35 whereby the cover may yield to allow for variations of volume of the enclosed liquid resulting from temperature variations. I

2. A cover for liquid compasses consisting of a yielding disc of 'transparent material and having an L-shaped flange at its periphery and a central circular flange on the inside.

JUSTUS LEONARD HASSEL. 

